Recorded article with anti-counterfeit measures

ABSTRACT

An object is to provide a recorded article or sticker whereby counterfeited articles and genuine articles can be visually distinguished in simple fashion in the market and wherein it is not possible to identify in the market the location and type of the anti-counterfeiting measures that have been taken. Both an overt region  3  (which can be recognized visually in the market) are printing using a color-change ink or liquid-crystal ink, for example, and a covert region  5  formed by for example optical retro-reflective printing (which cannot be recognized without using a special tool) are provided on the surface of the same recording medium. The overt region  3  and the covert region  4  may be arranged at different locations or may overlap, or may be positionally aligned. The overt letter/design pattern and the covert letter/design pattern may be the same or different. An overt recording that is printed using liquid-crystal ink may also function as a covert recording by employing a genuineness inspection method using a circularly polarized plate. A sticker may be provided with one or a plurality of cuts such that the sticker is broken when peeled off, so that it cannot be re-used.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of copending application Ser. No.10/469,282, having a § 371(c) date of Aug. 28, 2003.

TECHNICAL FIELD

The present invention relates to a recorded article such as for examplea printed article, with anti-counterfeit measures.

BACKGROUND ART

In order to prevent counterfeiting of recorded articles such as forexample printed articles produced by color copying technology using anoptical image scanner and color printer or in order to ascertaingenuineness by identifying whether a subject article is a forgery or agenuine article, recording or printing techniques are known in whichspecial optical characteristics are applied to the surface of theprinted article. Such recording techniques for preventing counterfeitingcan be classified into two types, called overt and covert. The specialoptical characteristics of the overt technique are exposed i.e. can beidentified simply by directly viewing with the naked eye under naturallight. The special optical characteristics of the covert technique arehidden and can only be identified by viewing under special opticalconditions or using special optical tools.

A typical example of an overt technique is recording or printing using acolor-change ink; this is disclosed in Laid-open Japanese PatentPublication No. H8-324169 or Laid-open Japanese Patent Publication No.H9-254520 or Laid-open Japanese Patent Publication No. H10-060303. Acolor-change ink has the property that the main wavelength of reflectedlight therefrom when white light is directed on to the surface of theink changes depending on the angle of incidence (angle of reflection).The perceived color of a surface printed with a color-change inktherefore changes when the angle of viewing is changed.

A typical example of a covert technique is recording or printingaccompanied by surface processing to produce optical retroreflectionproperties, as disclosed in U.S. Pat. No. 2,407,608 or Laid-openJapanese Patent Publication No. H10-97308, for example. Opticalretroreflection means a reflection characteristic whereby the angle ofincidence and the angle of reflection are substantially the same i.e. areflection characteristic in which incident light is bent back so thatthe reflected light is returned to the light source. A covertly recordedportion having optical retroreflection is of exactly the same color asthe surrounding region when viewed under natural light and so cannot bedistinguished, but can be distinguished from the surrounding region whenviewed using a special tool.

Since both overt techniques and covert techniques require special inksor special processes for processing, a recorded article manufacturedusing such techniques cannot be reproduced using a simple color copier.

A recorded article to which an overt technique has been applied and acounterfeit article manufactured by simply copying this using a colorcopier can be differentiated visually simply by ordinary viewing undernatural light. Accordingly, even supposing such a simple counterfeitproduct appears on the market, people in the market can easily noticethat it is not a genuine product. The effectiveness of overt techniquesin excluding simple counterfeit products from the market is thereforehigh. Other hand, since the location and type of such overt recording onthe article in question are apparent to the eyes of anyone, this gives aclue to other persons intending to imitate such overt recording.

In contrast, the presence of covert recording cannot be noticed bypeople in the market. There is therefore little likelihood of clues toimitate this covert recording being given to other persons. However,people in the market cannot normally identify the presence of covertrecording, so there is a high probability of people in the market beingsimply cheated even by simple counterfeit articles.

DISCLOSURE OF THE INVENTION

An object of the present invention is therefore to provide a recordedarticle or printed article with anti-counterfeiting measures wherebycounterfeited articles and genuine articles can be visuallydistinguished in simple fashion in the market and wherein it is notpossible to identify in simple fashion in the market the location andtype of the anti-counterfeiting measures that have been taken.

A further object of the present invention is to provide a security labelin the form of a label or sticker suitable for sticking onto for exampleproducts or product packaging, that can be employed for preventingcounterfeiting of products or for ascertaining genuineness.

A recorded article according to one aspect of the present inventioncomprises an overt recording formed by an overt technique and a covertrecording formed by a covert technique on the surface of the samerecorded medium. With this recorded article, genuineness can beascertained in simple fashion even in the market by means of the overtrecording and, even if counterfeit products appear imitating the overtrecording, genuineness can still be ascertained using the covertrecording. Also, a synergetic effect of the overt and covert recordingsis obtained in that the presence of the overt recording in this recordedarticle acts as a decoy making it difficult to notice the presence ofthe covert recording.

In a recorded article according to the present invention, it can bearranged that the overt recording and covert recording at leastpartially overlap. It can also be arranged to make the overt recordingand covert recording of different plan design in regard to for exampletheir shape or size. Such an arrangement makes counterfeiting even moredifficult.

The overt recording may be made extremely difficult to counterfeit byforming by for example superimposing liquid-crystal ink on acolor-change ink.

Also, when the overt recording and covert recording are superimposed,the covert recording may be formed by an optical retroreflection layercomprising minute transparent spheres arranged on a transparentreflecting layer. With such a construction, under natural light, thecovert recording is substantially transparent or close to transparentand the covert recording therebelow can be clearly seen. When viewedunder special conditions or using a special tool, the covert recordingcan be clearly seen.

The overt recording and covert recording can also be stacked in perfectalignment by making their plan design such as shape and size completelyidentical. If this is done, an even more effective decoy effect of theovert recording may be exhibited.

Also, the overt recording may be formed by superimposing liquid-crystalink on an underlayer of a specified color, or superimposing a backgroundregion around the overt recording or superimposing liquid-crystal ink onan underlayer of different color, or may also be formed by directlyemploying an underlayer of the above specified color, withoutsuperimposing liquid-crystal ink thereon. In this way, the overtrecording can also function as a covert recording.

In this way, ascertaining genuineness can be performed using the covertrecording function, by observing this recorded article, on which arecording has been formed that functions both as an overt recording anda covert recording, using liquid-crystal ink, through for example aclockwise circularly polarized plate and anticlockwise circularlypolarized plate, respectively.

A security label according to a further aspect of the present inventioncomprises an overt recording formed by an overt technique and a covertrecording formed by a covert technique on the surface of a singlerecording medium and further comprises an adhesive layer whereby thesecurity label can be stuck onto a subject article such as a product orproduct packaging. The overt recording is capable of producing colorchange depending on the angle of observation by selective reflection oflight. The covert recording is capable of being identified by means of aspecial tool or device.

Alternatively, the overt recording may be produced using aliquid-crystal material or may be produced using a material obtained bylaminating a metallic oxide layer and/or metal and thin-film mica glasslayer and/or silicon oxide.

Alternatively, the covert recording may contain a material that reflectsor transmits light of a specified spectral pattern with respect toinfra-red light, so as to enable the genuineness thereof to beascertained by comparing the spectral pattern of the light that isreflected or the light that is transmitted in respect of illuminationwith infra-red light with a spectral pattern that has been storedbeforehand in a specified tool or device.

Also, the area of this security label may be no more than 8 squarecentimeters.

Furthermore, the security label may be provided with a cut at one or aplurality of locations such that, if an attempt is made to peel off thesecurity label once it has been a fixed to a subject article, thesecurity label is broken and rendered incapable of re-use.

As the method of manufacturing a security label according to the presentinvention, an overt recording may be printed by an overt technique and acovert recording may be printed by a covert technique printing on thesurface of the same recording medium; the overt technique may be asilkscreen method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are diagrams of a recording surface printed with acolor-change ink using an overt technique;

FIG. 2 is a view showing the plan design of major parts of an embodimentof a recorded article according to the present invention;

FIG. 3 is a plan view showing the plan design of major parts of anotherembodiment;

FIG. 4 is a plan view showing the plan design of major parts of afurther embodiment;

FIG. 5 is a plan view showing the plan design of major parts of yet afurther embodiment;

FIG. 6 is a cross-sectional view showing an example of the constructionof a base portion of the cross-section, (for example, cross-sectionalong the line A-A of FIG. 2) of an overt region 3 of the printedarticle shown in FIG. 2 or FIG. 3;

FIG. 7 is a cross-sectional view showing an example of the constructionof a base portion of the cross-section, (for example, cross-sectionalong the line B-B of FIG. 2) of a covert region 5 of the printedarticle shown in FIG. 2 or FIG. 3;

FIG. 8 is a cross-sectional view showing a further example of theconstruction of the cross-section of an overt region 3 of the printedarticle shown in FIG. 2 or FIG. 3;

FIG. 9 is a cross-sectional view showing yet a further example of theconstruction of the cross-section of an overt region 3 of the printedarticle shown in FIG. 2 or FIG. 3;

FIG. 10 is a cross-sectional view showing the appearance when the overtrecording formed using the liquid-crystal ink shown in FIG. 8 and FIG. 9is observed through a circularly polarized plate that transmitsanticlockwise polarized light;

FIG. 11 is a cross-sectional view showing the appearance when the overtrecording formed using the liquid-crystal ink shown in FIG. 8 and FIG. 9is observed through a circularly polarized plate that transmitsclockwise polarized light;

FIG. 12 is a cross-sectional view showing an example of the constructionof a base portion of the cross-section of a region where the overtregion and covert region shown in FIG. 3 to FIG. 5 are superimposed (forexample the cross-section along C-C shown in FIG. 3);

FIG. 13 is a cross-sectional view showing a further example of theconstruction of the cross-section of a region where the overt region andcovert region shown in FIG. 3 to FIG. 5 are superimposed;

FIG. 14 is a plan view of an embodiment of a security label according tothe present invention;

FIG. 15 is a plan view of a further embodiment of a security labelaccording to the present invention;

FIG. 16 is a plan view of yet a further embodiment of a security labelaccording to the present invention; and

FIG. 17 is a plan view of yet a further embodiment of a security labelaccording to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described below.

In these embodiments, in each case, an overt recording (hereinbelow,simply referred to as an “overt”) formed by an overt technique and acovert recording (hereinbelow, simply referred to as a “covert”) formedby a covert technique are provided on the surface of the same recordingmedium. For the overt recording, for example recording is employed thatproduces a color change depending on the angle of observation byselective reflection of light (hereinbelow turned “color-changerecording”).

Specifically, as a material that forms selective reflection of light,there may be mentioned by way of example a liquid-crystal material or amaterial obtained by laminating a metallic oxide layer, metal, micaglass or silicon oxide or other material. The desired object can beachieved by preparing such a material as a printing ink and performingprinting therewith. Some description will now be given concerningselective reflection.

A liquid-crystal material (in particular a cholesteric liquid-crystal)has a structure in which the molecular arrangement is twisted little bylittle along the helical axis, so that the liquid-crystal as a wholeforms a helical structure. As is well known, such a structure providesproperties such as optical rotatory power, selective optical scatteringand circular polarization dichroism. Specific examples of such materialsinclude the BASF PALIOCOLOR (registered trademark) series. Also, amaterial produced by laminating a metallic oxide layer, metal, micaglass and silicon oxide (hereinbelow turned optical brightness pigment)reflects light of different wavelengths depending on the angle, due tothe different refractive indices of the laminated substances and soappears to human eyes as displaying color changes. Specifically, itindicates a material obtained by grinding to a suitable size a pigmentformed by laminating metallic oxide such as silicon oxide, titaniumoxide, aluminum oxide or iron oxide with a base material of lowtransparency such as thin flakes of mica or a material obtained bygrinding to a suitable size a material obtained by laminating silica anda layer that reflects light, such as a metal or a metallic oxide. Aspecific example thereof is PALIOCROM pigment (BASF trademark) or othermaterials. An ink of appropriate physical properties or performance isprepared by combining any of these materials in a manufacturing device(printing device).

FIG. 1 is a diagram of a color-change ink recording surface.

A color-change ink can be printed by ordinary printing methods. As shownin FIG. 1A, preferably the liquid-crystal material or optical brightnesspigment employed in the color-change ink consists in flat plate shapesof pigment 100 arranged in a regular attitude on the surface of arecording medium 200 for recording. As shown in FIG. 1A, by arrangingthe flat shapes of pigment 100 in a regular fashion, the angle ofreflection of the reflected light 400 with respect to the angle ofincidence of the incoming light 300 can be maintained constant. In thisway, a large color change of the color-change recording can be produced,which is desirable for an overt recording. In contrast, as shown in FIG.1B, if the flat plate shapes of pigment 100 are irregularly arranged onthe surface of the recording medium 200, the reflected light 600 isreflected with scattered angles (scattered reflection) with respect to aparallel incident beam 500. With a recording surface in such acondition, the desired excellent color-change characteristic cannot beobtained.

The magnitude of the color change was described with reference to thediagrams are FIG. 1A and FIG. 1B, but when the recording surface of anactual color-change recording is observed, it is found that thecondition of arrangement of the pigment is different depending on themethod of printing. For example, it has been found that a method ofprinting using the silkscreen method is suitable for an arrangement ofthe flat plate shapes of pigment 100 approaching the condition of FIG.1A.

On the other hand, in the case of a covert recording, the recordingcannot be recognized solely by the naked eye under sunlight or ordinaryillumination and may be adopted where recording is to be performed by aspecial recording method such that the recording can only be recognizedusing special equipment.

Specific examples that may be given include fluorescent ink orphosphorescent ink. Commercially available inks of this type may beemployed. Typically, with such inks, the recording pattern emits lightand may be observed by irradiating with ultraviolet light. Forirradiating with ultraviolet light, for example a “black lamp” may beemployed. Since the recording pattern does not emit light under sunlightor light from fluorescent lamps, it cannot be read. Such an ink may beused for printing at a position separate from the recording position ofthe ink used in the overt technique. Another type of covert recordingthat may be mentioned by way of example is recording using a recordingmethod that produces optical retroreflection. One method of recording toproduce optical retroreflection is for example to form a transparentreflective layer of a specified pattern in a given region and to spreadinnumerable minute transparent spheres thereon, covering this region. Acovert recording (pattern of the reflective layer) recorded by such amethod of producing optical retroreflection cannot be recognizedvisually under natural light, but can be seen if viewed for examplethrough optical equipment capable of illuminating it with intense lightfrom the same direction as the line of vision.

As a further covert recording technique, a recording technique may beemployed such that the spectral waveform of the intensity (or opticalreflectance, optical transmittance or optical absorbance thereof) of thereflected light or transmitted light therefrom when specified light isdirected on to the covert recording is a specified waveform. Forexample, a covert recording may be employed in which recording iseffected using ink containing infra-red absorbing (reflecting) materialhaving a high absorbance (or reflectance) specifically in regard toinfra-red light of wavelength of 650 nm or more. By employing such aninfra-red absorbing (reflecting) ink, the genuineness of a subjectarticle can be ascertained by comparing the spectral pattern of lightreflected from the subject article on irradiation with infra-red lightwith the correct spectral pattern of reflected light of this infra-redabsorbing (reflecting) ink, which has been stored beforehand in theinspection device. With this method of inspection, the spectral patternof the reflected light produced by infra-red light of the infra-redabsorbing (reflecting) ink is stored beforehand in the inspection deviceand, if it is ascertained that the spectral pattern of the reflectedlight from the subject article is different from the spectral pattern ofthe reflected light stored in the inspection device, the subject articleis deemed to be a counterfeit article whereas, if it is ascertained thatthe spectral pattern of the reflected light from the subject article isthe same as the spectral pattern of the reflected light stored in theinspection device, the subject article is deemed to be a genuinearticle. In order to facilitate inspection, infra-red reflecting(reflecting) ink as described above may be included in the recordedportion recorded with the overt recording technique.

FIG. 2 to FIG. 4 respectively show the plan design of major parts ofthree embodiments of a recorded article according to the presentinvention.

In the recorded articles 1A, 1B, 1C of FIG. 2 to FIG. 4, both an overtrecording region 3 recorded using an overt technique and a covert region5 recorded by a covert technique are provided on the surface of the samerecording medium. In the case of the recorded article 1A of FIG. 2, theovert region 3 and covert region 5 are arranged in separate,non-overlapping locations. In the case of the recorded article 1B ofFIG. 3, the overt region 3 and covert region 5 partially overlap. In thecase of the recorded article 1C of FIG. 4, the overt region 3 and covertregion 5 are stacked so as to be positionally aligned. Although notshown in the drawings, it is also possible to arrange one of the overtregion 3 and covert region 5 so as to include the other.

In the overt regions 3 shown in FIG. 2 to FIG. 4, letters, for example“PRINT” are printed using for example a color-change ink so as to have aspecial optical characteristic for the overt recording. The backgroundregion other than the letters “PRINT” in the overt recording region 3may be without the special optical characteristic for the overtrecording or may be printed for example using a color-change ink of adifferent color, to provide another type of overt recording, which canbe differentiated from “PRINT” when viewed. Also, conversely, only thebackground region, excluding the letters “PRINT” may be printed so as tohave the special optical characteristic for the overt recording.

Consequently, it can be seen that the letters “PRINT” or the backgroundin the overt region 3 have a special optical characteristic, for examplethe property that their perceived color changes depending on viewingangle, simply by viewing with the naked eye under natural light.

In contrast, in the covert region 5, for example the letters “GENUINE”are printed so as to have a special optical characteristic, for exampleoptical retroreflection, for covert recording. The background regionother than the letters “GENUINE” in the covert recording region 5 may bewithout the special optical characteristic for the covert recording.Also, conversely only the background region, excluding the letters“GENUINE” may be printed so as to have the special opticalcharacteristic for the covert recording. Whichever method is adopted,simply by viewing with the naked eye under natural light, the backgroundregion appears the same as the letters “GENUINE”, so the letters“GENUINE” cannot be read.

The letters “GENUINE” in the covert region 5 can therefore be read onlywhen viewed under special optical conditions or using a special tool;for example in the case of optical retroreflection, the letters can onlybe viewed when illuminated with light that is more intense than thebackground light, from the same direction as the line of view.

Furthermore, the covert region 5 and the background region 7 around theoutside of this appear the same when viewed merely with the naked eyeunder natural light, so these two cannot be distinguished. It istherefore normally not possible to tell whether or not a covert region 5is present on the recorded article 1 and where it is present on therecorded article 1.

In the recorded article having both overt and covert recordings shown inFIG. 2 to FIG. 4, genuineness can be ascertained in a simple manner evenin the market, using the overt recording but even if counterfeitarticles should appear imitating even the overt recording, genuinenesscan still be ascertained using the covert recording.

In addition, the presence of the overt recording acts as a decoy to thecounterfeiter, hiding the presence of the covert recording even moreeffectively i.e. the overt and covert recordings may be regarded ashaving a synergetic effect. That is, there is a stronger probabilitythan in the case of prior art articles, in which only a covert recordingis employed on its own, that the counterfeiter, noticing the presence ofthe overt recording, may not anticipate the presence of a covertrecording and may therefore be neglectful of efforts to search for acovert recording.

Furthermore, the presence of both overt and covert recordings togetheron the same recorded article makes counterfeiting itself extremelydifficult. Specifically, in fact, in the case of both overt and covertrecordings, even when these are employed alone, special inks or specialmethods of manufacture are necessary in order to imitate these exactly,so this is not easy because of the high cost. In these circumstances,the presence of both overt and covert recordings on the same recordedarticle requires an even more complex and high-cost method ofmanufacture, so counterfeiting to produce an exact imitation isextremely difficult. In particular, when, as shown in FIG. 3 and FIG. 4,the overt and covert recordings overlap, in this overlapping portion,the optical characteristics of both the overt and covert recordings actin combination, so elucidation of the materials and/or structure of thisportion is extremely difficult for the counterfeiter; even if thecounterfeiter knows these, it is difficult to achieve the same colortone or optical conditions, so, as a result, an exact imitation is verydifficult.

The plan design (i.e. the external shape and size of the regionsthemselves and the shape, size and arrangement and other particulars ofthe letters or designs recorded in the regions) of the overt region 3and covert region 5 shown in FIG. 2 to FIG. 4 can be freely determined.However, in a preferred embodiment, as in the examples of FIG. 2 to FIG.4, the patterns of the overt region 3 and covert region 5 are differentin regard to for example the size or type or arrangement of the lettersor designs. Such differences of pattern make manufacture of acounterfeited articles difficult due to the added complexity.

Furthermore, regarding the arrangement of the covert region 3 and covertregion 5, if these two regions are superimposed as described above, theadvantage is obtained that the method of manufacturing counterfeitsbecomes extremely difficult. On the other hand, if the overt region 3and the covert region 5 are arranged in completely different locations,the advantage is obtained that it is difficult to discover the covertrecording. In particular, if for example the overt recording is a largestriking pattern whereas the covert recording is a small patternarranged in a location that cannot easily be discovered, the decoyeffect of the covert recording is exhibited to even more advantage, sothat the covert recording is even more difficult to discover.

Furthermore, a plurality of variations in regard to the arrangementand/or patterns of the overt and covert recordings described above maybe employed in suitable combination, thereby further improvingdifficulty of counterfeiting.

FIG. 5 shows a plan design of major parts of another embodiment of arecorded article according to the present invention.

In the recorded article 11 shown in FIG. 5, an overt region 13 andcovert region 15 having exactly the same plan design are made to bealigned in position. Specifically, in these regions 13 and 15, forexample the letters “PRINT” have the special optical characteristics ofthe overt recording and also have the special optical characteristics ofthe covert recording, while the background area apart from the letters“PRINT” does not have these special optical characteristics or,conversely, only the background area, excluding the letters “PRINT” hasboth of the special optical characteristics of the overt and covertrecordings. Alternatively, the letters “PRINT” may have the specialoptical characteristics of the overt recording while the background areahas the special optical characteristics of the covert recording; orconversely.

In this way, even when overt and covert recordings of the same plandesign are aligned in position, the decoy effect of the overt recordingis effectively exhibited, hiding the presence of the covert recording.That is, there is a high probability that the counterfeiter will assumethat the overt region 13 consists solely of an overt recording and willnot expect this to be combined with a covert recording. As a modifiedexample, the overt and covert recordings of the same plan design mayoverlap, but shifted by a slight distance (for example a distancesmaller than the line thickness of the letters), or overt and covertrecordings of similar plan designs differing somewhat in size may bestacked in a concentric positional relationship.

FIG. 6 shows an example of the structure of the base portion of thecross-section (for example the cross-section A-A of FIG. 2) of an overtregion 3 of the recorded article shown in FIG. 2 or FIG. 3.

As shown in FIG. 6, the pattern of letters or design of the overtrecording (for example “PRINT”) is printed with color-change ink 23 onthe upper surface of the base 21. For the color-change ink 23, there maybe employed for example a color-change ink obtained by mixing flatpigment shapes 25 comprising for example a liquid-crystal material oroptical brightness pigment with ordinary ink. Printing using thecolor-change ink 23 may be performed by a special printing method inwhich the surface directions of the surfaces 25 of the flat pigmentshapes are aligned, for example by the silkscreen method.

Light which is incident onto the surface of the color-change ink 23exits as reflected light that is reflected by the internal flat pigmentshapes 25. When this happens, specified wavelengths are selectivelyemphasized by interference of the reflected light at the upper surfaceand the reflected light at the lower surface of the flat pigment shapes25. The wavelengths that are emphasized change depending on the angle ofincidence. Accordingly, as shown in FIG. 6, when for example beams ofwhite light 27, 31 are incident at different angles of incidence, therespective reflected beams 29 and 33 appear to have different colors.Consequently, the area that is printed with the color-change ink 23appears in a different color depending on the angle of view. Incontrast, the reflected beams 37, 41 of the white light beams 35 and 39that are incident on areas that have not been specially printed in thisway are all of the same color, so there is no color change depending onangle of view.

FIG. 7 shows an example of the structure of the base portion of thecross-section (for example, cross-section along the line B-B of FIG. 2)of the covert region 5 of the recorded article shown in FIG. 2 or FIG.3.

The example shown in FIG. 7 is an example in which a covert recording isconstituted by a recording method in which optical retroreflection isconferred thereon. As shown in FIG. 7, a transparent reflective layer 43is formed with letters or a design pattern (for example, “GENUINE”) ofthe covert recording on the upper surface of the base 21. On top ofthis, innumerable minute transparent spheres 45 are spread so as tocover the entire covert region 5 and are then fixed by an adhesive layer47.

Part of the upper surface below the minute spheres 45 above thereflective layer 43 is covered by a reflective layer 43. By selection ofthe material of the reflective layer 42, minute spheres 45 and adhesivelayer 47, reflection of light that has passed through the interior ofthe minute spheres 45 at the upper surface where the minute spheres 45are in contact with the reflective layer 43 may be facilitated or, onthe other hand, substantially all of the light that has passed throughthe interior of the minute spheres 45 may be arranged to exit to outsidethe minute spheres 45 without being reflected at the surface where theminute spheres 45 make contact with the adhesive layer 43.

When light is incident on a covert region 5 constructed in this way, thelight 49 that is incident on the region where the reflective layer 43 ispresent enters the minute spheres 45, so part thereof is reflected atthe surface of the minute spheres 45, producing retroreflection light51, that returns in the direction of the incident light 49. Part of theremainder of the incident light 49 is reflected at the surface of thebase 21 after exiting to the minute spheres 45 and exits in a direction(diffuse reflected light 53) completely different from that of theincident light 49. Also, the light 55 that is incident in the regionwhere the reflective layer 43 is not present enters the minute spheres45, so substantially all of this light is reflected at the surface ofthe base 21 after exiting the minute spheres 45 and exits in a directioncompletely different from that of the incident light 55 (diffusereflected light 59).

Consequently, under natural light that is incident with substantiallythe same intensity from all directions, the retro-reflected light 51does not stand out, since it is mixed with other diffuse reflectedlight, so the covert recording cannot be recognized with the naked eye.However, if the covert region 5 is illuminated with intense light fromthe same direction as the line of vision, the amount of light of theretro-reflected light 51 becomes larger than the diffuse reflected light53, so the covert recording can be seen.

FIG. 8 shows an example of another structure of the cross-section of theovert region 3 of the recorded article shown in FIG. 2 or FIG. 3.

In the example shown in FIG. 8, an overt recording is formed usingliquid-crystal ink. As shown in FIG. 8, letters or a design pattern (forexample “PRINT”) of the overt recording are printed with a specified ink61 on the upper surface of the base 21. On top of this, liquid-crystalink 63 having circular polarization dichroism is used to coat the entireovert region 3. As the specified ink 61, an ordinary colored ink may beemployed, or a color-change ink as described above may be employed or aliquid-crystal ink may be employed (in this case, the liquid-crystal inkis laminated). As the liquid-crystal ink 63, a cholestericliquid-crystal ink (for example BASF's PALIOCOLOR (registeredtrademark)) having optical properties such as optical rotator power,selective optical scattering and circular polarization dichroism may beemployed.

When light is incident on an overt region 3 constituted in this way, thelight 65 that is incident on the region of the specified ink 61 isdivided into two circularly polarized beams, anticlockwise beam 67 andclockwise beam 69, by the circular polarization dichroism of theliquid-crystal ink 63; the anticlockwise beam 67 is reflected by theliquid-crystal ink 63, while the clockwise beam 69 is transmittedthrough the liquid-crystal ink 63. When the clockwise beam 69 that hasthus been transmitted is incident on the specified ink 61, part thereof71 is absorbed while the remaining part (having the color of thespecified ink. 61) 73 is reflected. Consequently, the color obtained bycombining the anticlockwise beam 67 reflected by the liquid-crystal ink63 and the clockwise beam 73 reflected by the specified ink 61 isobservable by human beings.

In contrast, in the region where no specified ink 61 is present, thelight 75 that is incident in the region where for example the base 21can be seen is split into two circularly polarized beams, anticlockwisebeam 77 and clockwise beam 79, in the same way as described above, dueto the circular polarization dichroism of the liquid-crystal ink 63, theanticlockwise beam 77 being reflected by the liquid-crystal ink 63 andthe clockwise beam 79 being transmitted through the liquid-crystal ink63. The transmitted clockwise beam 79 is incident on the base 21, wherepart thereof 81 is absorbed and the remaining part (having the color ofthe base 21) 83 is reflected. Consequently, the color obtained bycombining the anticlockwise beam 77 reflected by the liquid-crystal ink63 and the clockwise beam 73 reflected by the base 21 is observable byhuman beings.

Since the color of the specified ink 63 and the color of the base 21 aredifferent, the color that is observed by human beings is different inthe region of the specified ink 63 and of the base 21. Furthermore, thisobserved color is not a simple color but rather is a color having aspecial optical effect due to the action of the liquid-crystal ink 63.For example, if the specified ink 63 is black, a rainbow-colored effectappears in the color that is seen. Also, if the specified ink 63 is acolor-change ink, the color that is seen is tinged with thiscolor-change effect. Also, if the specified ink 63 is a liquid-crystalink, a mirror effect appears. On the other hand, if the base 21 is forexample white, a pearl color effect appears in the color that is seen.In all cases, the color having a special effect obtained by theliquid-crystal ink 63 cannot be reproduced by a simple color copier.

FIG. 9 is yet a further example construction of the cross-section of theovert region 3 of the recorded article shown in FIG. 2 of FIG. 3.

The example of FIG. 9 is also an example in which an overt recording isformed using liquid-crystal ink. As shown in FIG. 9, first of all, acoating of the specified ink 61 is applied to the entire overt region 3on the upper surface of the base 21. On top of this, an overt pattern offor example letters or a design (for example “PRINT”) is printed withliquid-crystal ink 63 having circular polarization dichroism.

When light is incident onto the overt region 3 constructed as above, inthe region printed with the liquid-crystal ink 63, as already described,a color having a special effect obtained by combining the anticlockwisebeam 67 reflected by the liquid-crystal ink 63 and the clockwise beam 73reflected by the specified ink 61 is observed by human beings. Incontrast, in the region where there is no liquid-crystal ink 63,reflected light 67 of the color of the specified ink 61 is observed.

It should be noted that the construction shown in FIG. 8 and theconstruction shown in FIG. 9 could be combined. Specifically, an overtregion could be designed by combining three types of pattern, namely, apattern printed by overlaying a liquid-crystal ink 63 onto the specifiedink 61, a pattern in which printing is effected only with the specifiedink 61 and a pattern printed with the liquid-crystal ink 63 overlayingthe base 21.

Furthermore, the overt recording formed using the liquid crystal inkshown in FIG. 8 and FIG. 9 also has the function of a covert recording,due to the circular polarization dichroism possessed by theliquid-crystal ink. This will be described with reference to FIG. 10 andFIG. 11.

FIG. 10 describes the appearance of an overt region formed usingliquid-crystal ink 63 when viewed through an anticlockwise circularpolarization plate 101 that selectively transmits anticlockwise light.FIG. 11 shows the appearance of an overt region formed usingliquid-crystal ink 63 when viewed through a clockwise circularpolarization plate 103 that selectively transmits clockwise light.

As shown in FIG. 10, when viewed through the anticlockwise circularpolarization plate 101, of the reflected beams 67, 73, 77, 83 incomingfrom the region coated with liquid-crystal ink 63, only theanticlockwise beams 67 and 77 reflected by the liquid-crystal ink 63 areobserved on passage through the anticlockwise circular polarizationplate 101. Consequently, the region coated with the liquid-crystal ink63 appears in the same color irrespective of the optical characteristicsof the underlying layer (for example whether this consists of thespecified ink 61 or the base 21). That is, the pattern that is printedwith the specified ink 61 in the region coated with the liquid-crystalink 63 cannot be seen. However, the region that is coated with theliquid-crystal ink 63 and the region that is not thus coated (regionwhere the reflected light 87 is directly incoming from the specified ink61) can be distinguished by different colors.

Contrast, as shown in FIG. 11, when viewed through the clockwisecircular polarization plate 103, of the reflected beams 67, 73, 77, 83incoming from the region coated with the liquid-crystal ink 63, only theclockwise beams 73 and 83 that are reflected by the underlayer afterpassing through the liquid-crystal ink 63 are observed through theanticlockwise circular polarization plate 103. Consequently, in theregion coated with the liquid-crystal ink 63, the pattern printed withthe specified ink 61 and the pattern which is not thus printed can beclearly distinguished. However, the pattern of the specified ink 61 thatis coated with the liquid-crystal ink 63 and the pattern of thespecified ink 61 that is not thus coated appear with the same colorthrough the clockwise polarization plate 103 and so cannot bedistinguished.

Thus, when the overt region in which the liquid-crystal ink was employedis observed using the circular polarization plates, a differentappearance is presented to that seen simply with the naked eye.Consequently, even if a counterfeiter has imitated by another method thecovert region using the liquid-crystal ink (it is in fact possible toproduce a rainbow-colored effect or pearl colored effect and the likesimilar to that of a liquid-crystal ink by other methods), the fact thatthe article is counterfeit can still be ascertained by observation usinga circularly polarized plate. In this respect, the overt recording usingthe liquid-crystal ink also provides the function of a covert recording.For example, if a pattern as shown in FIG. 5 is manufactured usingliquid-crystal ink, it can naturally be manufactured in overt form andcovert form.

A circularly polarized plate can be created for example as follows.Specifically, a PVA film or the like is uniaxially extended and dyedwith iodine. If required, dyeing may be performed with another materialof desired color. In addition, a protective layer is applied to preventthe iodine escaping. A circularly polarized plate is created bysuperimposing a ¼ wavelength film and the above film. The distinctionbetween clockwise polarization and anticlockwise polarization plates isachieved by sticking on a linearly polarized plate and a ¼ wavelengthfilm at an angle offset by 45° with respect to the axis of linearpolarization.

FIG. 12 shows an example of the structure of the base portion of thecross-section (for example, cross-section along C-C shown in FIG. 3) ofa region where the overt regions 3, 13 shown in FIG. 3 to FIG. 5 and thecovert regions 5, 15 overlap.

As shown in FIG. 12, first of all, an overt letter or design pattern isprinted with color-change ink 23 on the surface of the base 21. On topof this, a covert letter or design pattern is formed by a reflectivelayer 43. On top of this, innumerable minute spheres 45 are spread so asto cover the entire covert region, and fixed by means of an adhesivelayer 47.

With such a region of overlapping overt and covert recordingsconstructed in this way, the retro-reflected light produced by theminute spheres 45 and reflective layer 43 is not noticeable undernatural light, so only the overt recording produced by the color-changeink 23 can be recognized; this appears to change in color depending onthe angle of view. However, when this is illuminated with intense lightfrom the same direction as the line of view, the intensity of theretro-reflected light described above is relatively increased, with theresult that the covert recording also becomes visible.

FIG. 13 shows another example of the construction of the cross-sectionof a region (for example, a cross-section along C-C shown in FIG. 3)where the overt and covert recordings shown in FIG. 3 and FIG. 5overlap.

As shown in FIG. 13, first of all, an overt pattern constituted forexample by letters or designs is printed with a specified ink 61(usually, for example, colored ink, color-change ink or liquid-crystalink) on the surface of the base 21. On top of this, the entire overtregion is coated with liquid-crystal ink 63. On top of this, a covertletter or design pattern is formed by a reflective layer 43. On top ofthis, innumerable minute spheres 45 are spread so as to cover the entirecovert region, and fixed by means of an adhesive layer 47.

With such a region of overlapping overt and covert recordingsconstructed in this way, the retro-reflected light produced by theminute spheres 45 and reflective layer 43 is not noticeable undernatural light, so the overt recording (pattern printed with thespecified ink 61) covering the liquid-crystal ink 63 is seen with acolor having a special optical effect. When illuminated with intenselight from the same direction as the line of view, the intensity of theretro-reflected light described above is relatively increased, with theresult that the covert recording (pattern of the reflective layer 43)also becomes visible.

FIG. 14 to FIG. 17 show respectively plan views of different embodimentsof a security label according to the present invention.

The security labels are stickers having an adhesive layer on one facethereof and are employed by sticking onto a subject article (for examplevarious types of product) itself or a package of the subject articleswith the aim of protecting these from counterfeiting. Overt and covertrecordings are made on the face on the opposite side to the adhesivelayer of these security labels. The manufacturing cost of sticking asticker on which overt and covert recordings are made onto the surfaceof a subject article or packaging may be lower than that of making overtand covert recordings on the surface of the subject article itself orthe packaging itself. It is desirable that a re-use prevention functionshould be provided so that it is not possible to peel off such securitylabels once they have been stuck onto a subject article and this hasbeen sold in the market, in order to stick the label on again onto acounterfeit product. In order to prevent re-use, for example, theadhesive strength or adhesive capability of the adhesive layer isdetermined such that once the label has been peeled off the adhesiveforce is substantially eliminated. As the adhesive employed in theadhesive layer, there may be mentioned by way of example adhesives ofthe type in which a resin having for example an acrylic resin-based orepoxy-based skeleton is dissolved in a solvent and oxidativepolymerization of the resin constituents is produced by drying thesolvent. Alternatively, in order to prevent re-use, for example one or aplurality of cuts may be provided in the security label such that if anattempt is made to peel off the security label from the subject articleor packaging, the security label is broken or torn. These cuts may beset at will in accordance with the size or shape of the label.

As the area of such a security label, there may be mentioned by way ofexample an area of no more than 8 square centimeters. With a securitylabel of such a small size, there is little risk of impairing theexternal design of the subject article or packaging of the subjectarticle onto which this label is affixed, the manufacturing costs of thelabel can be kept low and the step of sticking it onto the subjectarticle presents no difficulties.

The security label 200-1 shown in FIG. 14 is a circular sticker ofradius for example 15 mm. The portion 200-2 of the letters “EPOON” onthe surface of this security label 200-1 is an overt recording recordedwith color-change ink using for example a liquid-crystal material. Thisovert recording 200-2 is printed by for example a silkscreen methodprinting device. The portion of 200-3 of the letters “Genuine”designated in the Figure with the broken line is a covert recordingprinted with an offset type printing device using for examplefluorescent ink. This covert recording 200-3 employing fluorescent inkcannot be recognized simply with the naked eye under natural light andcan only be recognized when illuminated with ultraviolet rays using“black light”.

An adhesive layer, not shown, is provided on the back face of thissecurity label 200-1. This security label 200-1 is provided with cuts200-4 directed from the outer edge towards the interior at for examplethree locations. The length of these cuts 200-4 is for example about ½of the radius of this security label 200-1. When an attempt is made topeel off this security label 200-1 once it has been stuck on to forexample a subject article or the packaging thereof, the security labelbreaks at the location of the cut 200-4, making re-use impossible.

The security label 300-1 shown in FIG. 15 is a rectangular sticker offor example height 20 mm, width 40 mm. The portion 300-2 of the letters“EPOON” on the surface of this security label 300-1 is an overtrecording printed by the silkscreen method using ink containing forexample optical brightness pigment. The ink that is used for theprinting of this covert recording 300-2 contains infra-red absorbingmaterial (for example material whose optical absorbance in thewavelength band of 650 nm or more is particularly higher than that inother wavelength bands). Consequently, when specified light containinginfra-red light is directed on to this covert recording 300-2, reflectedlight having a specified spectral waveform is obtained and the spectralwaveform of this reflected light can be checked using a specialinspection device in which this spectral waveform pattern is previouslystored. This overt recording 300-2 therefore functions as a covertrecording. Also, the portion 300-3 of the letters “Genuine” illustratedby the broken line is a covert recording printed by offset printingusing for example phosphorescent ink. This covert recording 300-3employing phosphorescent ink cannot be recognized simply with the nakedeye under natural light and can only be recognized for example whenilluminated with ultraviolet rays using “black light”. An adhesivelayer, not shown, is provided on the back face of this security label300-1. Cuts 300-4 are provided as shown at the four corner portions ofthis security label 300-1 so as to break when the security label ispeeled off.

The security label 400-1 shown in FIG. 16 is a diamond-shaped sticker ofarea for example 6 square centimeters. The portion 400-2 of the letters“MAOH” on the surface of this security label 400-1 is an overt recordingrecorded with a color-change ink containing for example liquid-crystalmaterial. This overt recording 400-2 is printed with for example asilkscreen method printing device. Also, for example a star-shapeddesign portion 400-3 indicated by broken lines is a covert recordingprinted with an offset type printing device using for examplefluorescent ink. This covert recording 400-3 can only be recognized byviewing under illumination with ultraviolet light using for example“black light”. An adhesive layer, not shown, is provided on the backface of this security label 400-1. In addition, cuts 400-4 are providedas shown at two corner portions of this security label 400-1.

The security label 500-1 shown in FIG. 17 is a star-shaped sticker offor example area 7.5 square centimeters. The portion 500-2 of theletters “Long Life” on the surface of this security label 500-1 is anovert recording recorded with a color-change ink containing for exampleliquid-crystal material. This overt recording 500-2 is printed with forexample an offset type printing device. Also, the portion 500-3 of theletters “E, P, O, O, N” indicated by broken lines is a covert recordingprinted with an offset type printing device using for examplefluorescent ink. An adhesive layer, not shown, is provided on the backface of this security label 500-1. In addition, cuts 500-4 are providedas shown at two recessed corner portions of this security label 500-1.

While embodiments of the present invention have been described above,these are given by way of example for description of the presentinvention and it is not intended that the scope of the present inventionshould be restricted solely to these embodiments. The present inventioncan therefore be put into practice in various other modes withoutdeparting from the essence thereof.

A recorded article according to the present invention may be used toprevent counterfeiting of a product or to check the genuineness orthereof, by being applied to the product itself, which may be of varioustypes manufactured of various materials such as paper, plastics, metalor wood, or to the product packaging or ancillary articles such asguarantees associated with the product. Also, a security label accordingto the present invention may be utilized for prevention of productcounterfeiting or checking of genuineness, by being stuck onto productsof various types as described above, the packaging of these products orancillary articles associated with these products.

1. A method of manufacturing a security label wherein an overt recordingis printed by an overt technique and a covert recording is formed by acovert technique on the same recording medium and the printing by saidovert technique is silkscreen method printing.